2′-Deoxynucleosides and their analogues are therapeutically important agents. For example, gemcitabine, i.e., 2′-deoxy-2,2′-difluorocytidine, can be used to treat viral infection and cancer. See, e.g., U.S. Pat. Nos. 4,526,988 and 4,808,614.
In general, 2′-deoxynucleosides each have more than one chiral center and can occur as multiple stereoisomers. Not all stereoisomers are therapeutically active. Several stereoselective synthetic routes for 2-deoxy-β-nucleosides have been developed. None of them are satisfactory.
There is a need to develop a more effective route for stereoselectively synthesizing 2′-deoxynucleosides.